Back carriers with one or more shoulder straps are well known from the prior art. The wearing comfort of such back carriers depends on how well the height of the user and the length of the back plate of the back carrier can be adapted to each other.
In addition, back carriers can be provided with or without a hip belt. In a back carrier without a hip belt, the weight of the back carrier and of its load is transferred to the shoulders of a user largely via shoulder straps. The back carrier rests on the lower back of the user via a user contact surface, and the shoulder straps lie on the shoulders of the user. The shoulder straps are fastened to an upper fastening location of the back carrier. When the back carrier is being worn, these fastening locations lie below the shoulders of the user in the vertical direction. A relatively large contact surface of the shoulder straps on the shoulders and the back of the user can thus be achieved in order to distribute the applied weight across a large surface area.
JP 2013-091203 A discloses a back carrier in which several upper fastening locations are provided. Such a back plate is stiff and, when using adapted fastening locations, a very considerable length of the back plate protrudes upward and can get in the way when using the back carrier.
In a back carrier with a hip belt, the load on the shoulders is significantly reduced, since at least a large part of the weight is transferred from the hip belt to the user's waist. Only a small part of the weight is transferred to the shoulders of the user via the shoulder straps.
U.S. Pat. No. 6,536,641 B1 discloses a back carrier with a system for changing the distance between the hip belt and the upper fastening location of the shoulder strap. For this purpose, two rods are provided at the lower end of the back plate and can be pulled out steplessly from the back plate, between which rods a padding is held for resting on the region of the user's hips. The upper end of the shoulder strap is arranged on the back plate, while the lower end is arranged on the rod. Telescopic systems have a low level of stiffness and are expensive to produce. The extension of the back plate in the downward direction makes it difficult to park the back carrier safely on the ground. Moreover, the center of gravity of the loaded back carrier climbs higher relative to the user's back, which impairs wearing comfort, particularly on uneven ground.
If the same back carrier is intended to be used with different carrying systems (with or without hip belt in addition to the shoulder strap) and if the hip belt or the contact surface is to be arranged at the same height on the back plate, it is necessary to adapt the carrying system and its attachment to the back plate.